Hi Littlefoot,

Here's the reason why there are two windows. 
The main canvas is a transactions screen -  On the main canvas is a master detail block 
Master block has transaction header information and detail block has the transaction detail records (line items).
The master data block is based on the transactions table. 
The detail block is based on transaction_items table.
The two buttons are distribute and distribute all .
When the user has to distribute the amount on a single line item - he would click distribute button. Select the account number the amount has to be distributed, hits close and he is back to main canvas.
But if there say 45 line items it is not easy to click the distribute button each time and distribute the amount to an account.
Hence the distribute all button.... here he will select the account number and the amount for all the 45 line items has to be distributed to a single account. 
This the reason there are two buttons, two windows and two blocks in the form for distribute button and distribute all button.